Bonded Wafer Stress Prediction for Stacked Packaging Yield

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The semiconductor industry faces challenges in managing yield and reliability due to fabrication errors in bonded wafers, particularly issues related to centricity, shape-induced stress changes, and bonding interface stress, which can lead to defects and equipment damage.

Innovation Solution

A method and system for measuring top and bottom wafer shapes, determining shape-changed induced stress, and calculating bonding strength using a processor and a model, such as a hypermodel or machine learning algorithm, to improve bonding parameters and reduce failure risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If thinning or grinding processes are used to reduce wafer thickness, then the target thickness is achieved, but shape-induced stress changes occur leading to bonding failure and local cracks

Engineering Contradiction:

Improvewafer thicknessVSAvoidbonding strength

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent applies preliminary action by measuring wafer shape and calculating shape-induced stress changes before the thinning or grinding process. This allows prediction of bonding strength and identification of high-risk areas before damage occurs, enabling preventive measures to be taken

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by using measured wafer shape data and stress calculations to provide information about bonding strength and defect risks. This feedback loop allows process parameters to be adjusted based on predicted outcomes, improving reliability while achieving target thickness

Inventive Principle:

Principle #23Feedback

2Volume of moving object

If thinning processes are performed after bonding, then target thickness is achieved, but local cracks and grinding debris enter from the edge damaging devices

Engineering Contradiction:

Improvebonded wafer thicknessVSAvoidlocal crack and debris contamination

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary measurement of wafer shape and calculation of stress changes before thinning to identify areas susceptible to cracking. This allows preventive measures to be implemented before cracks propagate or debris enters during the thinning process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces direct mechanical inspection with a computational approach, using shape measurement data and stress modeling to predict bonding strength and defect risks without requiring physical testing that could introduce damage

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If bonding pitch is decreased to increase device density, then productivity improves, but delamination becomes more likely at bonding interface due to insufficient stress release space

Engineering Contradiction:

Improvedevice densityVSAvoidbonding interface stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses feedback from shape measurement and stress calculation to provide information about bonding interface stability. This allows process parameters to be optimized for high-density configurations while maintaining reliability by identifying and addressing stress concentration areas

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies parameter changes by using shape measurement data and stress modeling to determine optimal bonding parameters for high-pitch configurations. This enables adaptation of bonding conditions to maintain reliability as device density increases

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If shape-induced stress is not considered in post-bonding processes, then process simplicity is maintained, but failure risk cannot be reduced

Engineering Contradiction:

Improveprocess complexityVSAvoidbonding reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent replaces complex physical testing and trial-and-error approaches with computational stress analysis based on shape measurement data. This provides reliable failure risk assessment without requiring complex experimental setups or iterative testing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces shape measurement and stress calculation as an intermediary between process planning and actual manufacturing. This intermediary step provides critical information about bonding strength and failure risks without requiring direct physical testing of the bonded structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250140615A1Yield improvements in stacked packaging

Publication Date: 2025.05.01 KLA CORP

AI summary

Shape-changed induced stress for a target thickness of a bonded wafer can be determined. A bonding strength for the bonded wafer can then be determined using the shape-changed induced stress. Bonding parameters can be determined for the bonding strength. The bonding strength that is determined can be compared with an inline bonding strength for formation of the bonded wafer.